First run of the PVLAS experiment: Dark matter candidates production and detection

The PVLAS experiment is designed to study photon-photon interactions in the low energy region using optical techniques. In the PVLAS apparatus photons from a laser beam interact in vacuum with an external magnetic field, and the two-photon interaction results in the possible production of neutral, nearly massless, scalar/pseudoscalar particles. Evidence of particle production is extracted from the study of the light polarisation state after traversing a region where a the magnetic field is provided by a superconducting dipole magnet. Polarisation measurements are conducted using a very sensitive ellipsometer based on a high finesse (~100000), 6.4 m long, Fabry-Perot optical resonator. The PVLAS apparatus is now fully integrated and operational: the first commissioning run with a 4.0 T field has been successfully completed, the first data taking runs have been conducted, yielding a total integration time of about 20 hours, and data analysis is now in progress. We will present details from the commissioning run and preliminary results from the data runs